Thousands have abandoned their homes in northern NSW and hundreds of people rescued from floodwaters as the remnants of ex-tropical cyclone Debbie bore down, dumping a staggering amount of rain on the region.

If you're wondering why battery storage is still on the fringe of the energy debate in Australia, and also perhaps why power prices are high, just ask Tony Marxsen, the head of the country's energy markets.

The world is 33 months into its biggest recorded coral bleaching event with little sign of it ending, raising the prospect that coral mortality on the Great Barrier Reef will increase "significantly" from the quarter already lost in the past year, scientists say.

The controversial waste management magnate behind plans to build a massive "energy from waste incinerator" near homes in western Sydney defended his environmental track record before a fiery parliamentary inquiry into the safety of the proposal on Thursday.

A second day of heavy pollution levels over Sydney caused by controlled fires in the Blue Mountains has prompted calls for earlier warnings and a review of the costs and benefits of hazard-reduction burns.

Australia's biggest coal-fired power stations are permitted to dump toxic pollutants on nearby populations far in excess of overseas counterparts, even those in China, a survey by Environmental Justice Australia reveals.

The NSW government is claiming waste recycling rates about twice real levels and is refusing to amend its published data despite being presented with more accurate industry-sourced information, green groups say.